A) Field of the Invention
The present invention relates to a clutch disc damper assembly, and more particularly, to a clutch disc damper assembly having a separated hub and a friction generating construction having multiple friction generating portions.
B) Description of the Related Art
A damper mechanism in a clutch disc for use in a motor vehicle typically includes a power input plate, a power output hub formed with a radially extending flange, and an elastic element elastically coupling the power input plate and the flange.
Alternatively, clutch discs have also been provided with a hub, an intermediate plate and a power input plate where a first elastic element having a relatively low rigidity which couples the intermediate plate and hub in addition to a second elastic element which couples the power input plate and the intermediate plate. This type of damper disc assembly is such that relative torsional displacement between the input plate and the hub includes two levels of vibration damping due to the characteristics of the two springs, the first spring having characteristics of low rigidity and the second spring having characteristics of high rigidity.
Further, such a damper disc assembly may include a first friction element positioned between the power input plate and the hub so as to generate friction force (hysteresis torque) upon relative rotation between the power input plate and the hub. A second friction element is disposed between the intermediate plate and the power input plate.
In such a separate hub/intermediate plate type damper disc assembly, a minor torsional vibration, when transmitted, causes relative rotation between the power input plate and connecting plate, and the power output hub. This results in the elastic element of low rigidity to repetitively expand and be compressed, and the first friction element slides between the power input plate and the connecting plate to create a small friction force. A major torsional vibration, when transmitted, causes relative rotation between the power input plate, and the intermediate plate and power output hub. This results in the elastic elements to repetitively expand and be compressed, and the second friction element slides between the power input plate and the connecting plate to cause a relatively large friction force. The property of low rigidity and small friction force is effective for dampening minor torsional vibrations while the property of high rigidity and large friction force is effective for dampening major torsional vibrations, and thus, any vibration can be dampened well.
The damper clutch disc assembly in the prior art has two separate and distinct friction elements respectively engaged with the power input plate so as not to rotate relative to it but to be movable relative to it in axial directions in order to generate various levels of the friction force corresponding to various levels of the torsional vibration. This leads to increase in components like engaging elements in the friction elements.